1. Field of the Invention
The present invention relates to skis utilized in winter sports, and adapted to slide on ice and snow.
2. Related Subject Matter
The subject matter in this patent is related to the commonly assigned U.S. patent application Ser. No. 07/548,204, filed on Jul. 5, 1990, and the following commonly assigned U.S. Pat. Nos. 4,795,184, issued on Jan. 3, 1989; 4,838,572, issued on Jun. 13, 1989; 4,869,523, issued on Sep. 26, 1989; 4,971,349, issued on Nov. 20, 1990; 5,000,475, issued on Mar. 19, 1991; 5,002,300, issued on Mar. 26, 1991; 5,002,301, issued on Mar. 26, 1991; 5,033,765, issued on Jul. 23, 1991.
3. Description of Background and Relevant Information
A ski generally comprises a body having an upper surface, and a lower sliding surface provided with metallic corners along the lower lateral edges thereby defining the width of the sliding surface. The width of a ski is relatively small compared to its length; and the front end of the ski is curved upwardly to form a spatula. Typically, the width of a ski is narrower in the central region than in either the front or rear regions, the width being a maximum at the front of the ski adjacent the spatula. The thickness of the ski generally is greater in the central portion where the binding for the ski is located. Then in either the front or rear portions of the ski.
Conventional skis generally have a composite structure in which different materials are combined in a manner such that the material serves a specialized function taking into account the distribution of mechanical stresses in the ski. A typical composite structure comprises mechanical resistance elements, or reinforcing elements, of a material having a high mechanical resistance to strain, and substantial rigidity so as to resist flexional and torsional stresses produced in a ski during its use. The conventional structure, furthermore, may include filler elements, and sometimes shock absorption elements.
The two principal modern composite structures finding current wide scale application in skis are the so called "sandwich" and "casing" structures. In a typical casing structure, such as described in French Patent No. 985,174, and in FIG. 3 of French Patent No. 1,124,600, the ski comprises an internal core made of cellular material which may be partially hollow, and mechanical resistance elements surrounding the core in the form of layers that constitute a casing for the core.
In a typical sandwich structure, such as described in U.S. Pat. No. 4,405,149, the ski comprises a central core made of a cellular material, which may be partially hollow, reinforced above and below respectively, by an upper resistance layer and a lower resistance layer. It has been observed that a sandwich structure provides a ski that has the best straight line sliding characteristics, i.e., when the ski moves in the longitudinal direction of the ski. 0n the other hand, the lateral gripping quality of such a ski during banking or turning maneuvers is not optimal. For this reason, skis having a casing structure are preferred in order to optimize skiing on inclines or in executing turns, since a casing structure has superior flexional elasticity and mechanical resistance properties, and a substantial resistance to torsion along the longitudinal axis of the ski. Skis having a casing structure provide optimum lateral gripping qualities during banking or turning maneuvers. 0n the other hand, the straight line sliding characteristics of such skis are less desirable than skis having a sandwich structure.
As a result, it is customary to select skis on the basis of the use to which the ski will be put. For example, a ski having a sandwich structure is selected for downhill competition, because this structure has superior sliding Characteristics, and a ski having a casing structure is selected for slalom competition because the casing structure has superior ice-gripping qualities.
An object of the present invention is to provide a new and improved ski which produces novel and advantageous technical effects, thereby avoiding the above-described deficiencies of the prior art.